FERTILIZATION IN PLANTS AND UNICELLULAR ORGANISMS 325 



for multiplication, that it is not a life-awakening process, but is 

 a process of a unique kind, which means something quite different. 

 The whole conception of the awakening of life in the germ is anti- 

 quated and out of harmony with the present state of our knowledge. 

 Life never legins anew, as far as we can see, and apart from the 

 possibility that, unknown to us, a spontaneous generation ( Urzeugung) 

 of the lowest forms of life is still taking place, life is continuous and 

 consists of an infinite series of living forms between which there is 

 no real interruption. Life, in fact, is like a continuous stream, the 

 larger and smaller waves of which are particular species and indi- 

 viduals. Only a few decennia ago a morphologist, who was rightly 

 held in high esteem, could champion the idea that the mature ovum 

 of animals was lifeless material, which had to be quickened in order 

 to develop, but now such a theory is untenable, since we have 

 become aware of the phenomena of maturation in the ovum, and 

 know that most important vital processes, the reducing divisions, 

 take place at the time of maturation, quite independently of fertili- 

 zation. 



Thus we do not even require to take into account the conjuga- 

 tion of unicellular organisms to make it clear that amphimixis is not 

 the cause of the origin of new individuals, but a process, sui generis, 

 which may indeed be associated with the beginning of embryonic 

 development, but which may also occur independently of it, as we 

 see in the case of unicellular organisms. If, on the one hand, we see 

 development taking place in spores and parthenogenetic ova in- 

 dependently of amphimixis, and on the other hand amphimixis 

 occurring without reproduction in unicellular organisms, we must 

 regard the two phenomena, amphimixis and reproduction, as processes 

 of a distinct kind, which may, however, occur in association with and 

 interdependence upon each other. 



It was by chance that human observation brought the latter fact 

 to light first, and therefore led us for so long to accept the idea that 

 fertilization, that is, amphimixis, and development, that is, reproduction, 

 are one and the same ; and thus it happens that even now there 

 are many naturalists who cannot rid themselves of the idea that 

 amphimixis, if not a life- awakening, is at least a Ufe-reneiving process, 

 a so-called ' process of rejuvenescence.' 



More than ten years ago ^ I disputed this view, and since then 

 the facts which make it untenable have become more and more clear. 

 Notwithstanding this I see that it is still adhered to, at least in a 



1 Die Baleutung der sexuellen Fortpflamung fiir die aelektionslUemie, Jena, 1886. 



X 2 



